Improvement in the construction of screw-propeller blades



UNITED STATES PATENT OFFICE,

CHARLES C. GATES, OF ALBANY, NEW YORK.

IMPROVEMENT IN THE CONSTRUCTION 0F SCREW-PROPELLER BLADES.

Specification forming part of Letters Patent No. 51,4146, dated December12, 1865.

Yo all 'whom tt may concern:

Be it known that I, CHARLES C. GA'rEs, of the city and county of Albany,in the State of New York, have invented a new and improved method of'Forlning Propeller-Blades; and I do hereby decla-re the following to bea full and exact description of the saine, reference being had to theannexed drawings, making a part of the specification, in which- Figure 1is the formula for the construction ofthe blades, and Fig. 2 a plan ofthe curves on the acting-surface of the blades, and Fig. 3, aperspective side elevation of one of the blades.

The nature of my illventioll relates to the lnanller of' constructingpropeller-blades, so as ill their revolutions to give'the water acelltrifugal actioll on the blades7 acting-surface, tllereby receivingall increasing impetus, vet confining the water within the outer curvean d finally throwing the water ofi' directly aft, by lnealls of curvedlilies as combined with the various allgles of the staves with the lilleof shaft, said curved lines giving the form ofeach particular stave,they being of various widths, and also as to tlleir various thicknessesand taper or wedging forms. The acting-surface of' the blades (at thehub only) have the f'ornl ot' a helix or lille of a screw, alld at theouter curve, only, they lie ill a plane, the area of the blades7 surfaceconforming to the various curves alld tapering thicknesses ofthe stavesand their relative angles.

The following description will enable others skilled ill the art to makeand use llly invention.

The blades are forlned, as in the ordinary lnanller of construction, bygluing each stave together relatively to its curves and the requiredpitch or angle, Fig. l being a formula as it lies wholly ill a plane, itbeing given for the purpose of' showing the lnanner of' producing theforms of staves, they each bein g of various lengths and thicknesses.The line of' clearance being giving fore and aft, I then draw a straghtlille ofthe required angle with line of shaft alld respectively to thewheels dimensions to O, it being the extreme of the blade aft, as shownin Fig. l. Then dividing said line equally into any given number ofspaces, I also divide on the center line the hubs length, which is abouthalf the wheels cleavance (fore and aft) into the same given number ofspaces, the hub being thrown forward for the purpose of throwing amajority of the staves at a greater angle aft with line of shaft. I thendraw straight lines from the division points l 2 3 4, &c., at thehub-center, through their respective divisions l 2 3 4, etc., on lille Ab O to the outer curves, A d O, of' blade, said curve being subject toalterations so as to conform with lille A b O. Fig.2 is to show theacting-surface of' the blades, also showing the line A b O to be acurved one, and also equally divided with the saine given number ofspaces l 2 3 4, Sac., of' formula, and with their respective radii equalwith those of the formula. I then draw f'ronl the hubs centerradiatinglilies, as shown in red ink, through the division-points to the outercurve ofblade; and then from the intersecting-points l 2 3 4, &c on t-hecurved lineA b C, I. set back about two-thirds of each division for thepurpose of forming curved lines, (said curves lgiving the form of eachparticular stave.) Then iroln the radiating lines at the outer curve, Ad O, I draw concave lines, intersecting them at the two-third divisionof each space on lille A b O, then receding until they gradually assumeconvex lines and tangenling the radiating lilies from the hub center.The concavity or dishing-surface of' the blade is produced by saidcurved lilies alld gradually flattening at all illereased radius onlille A b O until itconforlns with a straightline at O. The lappingsurface for gluing the staves together are relative to the requiredthickness for strength and the angle ofblades. After the bladesbeingformed I then cut away from A and H to the hubs surface several ot'the outer staves for the purpose of lessenillg the vacuuln and drag onthe back of' the blades, the back ofthe blades then being chanlfered toan edge to facilitate its passage through the water.

I anl aware that lines of a plane have been used by others, also theincreasing edges of blades, therefore, I do not claim, broadly andirrespective of construction, such devices; but

What I do claim, and desire to secure by Letters Patent, is

The manner of forming the blades by their irregular curves and Widthsand unequal thicknesses of staves, as combined and arranged asspecified, and for the purpose set fortll.

CHARLES C. GATES.

Witnesses:

S. M. CLARK, F. E. SPINNER.

